Photopolymerizable, coatable plastisol

ABSTRACT

Photopolymerizable plastisol and organosol photoresist and solder mask coating compositions are described herein. These compositions include an ethylenically unsaturated photopolymerizable liquid plasticizer; a particulate, thermoplastic resin is dispersed in the plasticizer, the said resin having a midpoint Tg greater than 110 DEG  C. and an acid number greater than 110; a tertiary amine stabilizer; and a photoinitiator. The organosol includes a diluent along with the other ingredients.

This application is a continuation-in-part of U.S. Ser. No. 07/546,814,filed Jul. 2, 1990, entitled "A Photopolymerizable, Coatable Plastisol"now abandoned.

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to photocurable plastisol and organosol coatingcompositions. More particularly, it relates to fusiblephotopolymerizable plastisol and organosols which are photoimagableresists and solder masks.

The plastisol and organosol compositions that are described herein haveseveral advantages over other photoresist and solder mask coatingcompositions. Both the organosols and the plastisols avoid the problemssuch as non-uniform mixing and inaccurate metering that is found withtwo part liquid systems. Further advantages to the present system arecontact imagability, aqueous alkali developability, good resolution, andthe ability to be used with a variety of application techniquesincluding screen printing.

In addition to these advantages, the present compositions haveadvantages over known plastisol-organosol compositions. Specifically,known plastisol-organosols disadvantageously, do not have adequate shelflives, and in fact plastisol-organosol systems of industry,characteristically, suffer from short shelf lives. Theplastisol-organosol compositions described herein, however, have a shelfstability that provides remarkably long shelf lives. These long shelflives are a very needed advantage for the commercial marketing of thephotoimagable resist and solder mask plastisol coating composition.

BRIEF DESCRIPTION

Fusible photopolymerizable plastisol photoresist and solder mask coatingcompositions comprise an ethyllenically unsaturated photopolymerizableliquid plasticizer; a particulate, thermoplastic resin which isdispersed in the plasticizer, the said resin having a midpoint Tggreater than 110° C. and an acid number greater than 110; a tertiaryamine stabilizer selected from the group consisting of triethyl amine,N-butyl diethanol amine, 4-methyl morpholine, and dimethyl aminoethanol;and a photoinitiator. To obtain an organosol, a diluent is used alongwith the other ingredients.

In fact, these particular stabilizers can be combined with a plastisolcomprising the above described resin dispersed in a plasticizer. Animproved (longer) shelf life is obtained. Any plasticizer, including anon-reactive plasticizer (such as dioctyl phthalate) can be used.

The coatable, photoreactive plastisol compositions are fused to formcontact imagable layers that are aqueous developable. For aqueousdevelopability the resin included in the plastisol is soluble and/ordispersible in a basic aqueous solution. This eliminates a resin that isnot soluble or disperible in aqueous base. Polyvinyl chloride (PVC)resin (including homopolymers and copolymers), is not included in theinstant plastisols unless it allows aqueous developability.

Although non-PVC plastisols (containing no resin having vinyl chloridemonomer) are traditionally known to have short shelf lives the instantcombination provides stable, photosensitive plastisols because of thetertiary amine stabilizer. With the present compositions a shelf life inexcess of 6 months is not unusual. If the tertiary amine stabilizer isnot included, the photopolymerizable plastisol will have little to noshelf-life.

DETAILED DESCRIPTION

To make these coatable dispersions, the resin polymer is dispersed inthe liquid ingredients. The ingredients can be mixed in any convenientorder. A preferred method, however, is to add the amine to the liquidingredients, followed by dispersing the resin.

The liquid plasticizers used for the present plastisol and organosolcompositions are ethyllenically unsaturated. They providephotopolymerizability to the coating compositions. The plasticizers canbe selected from monomers, oligomers, and prepolymers. Preferredphotoreactive acrylate species have two or more acrylate moieties.Highly preferred plasticizers are water sensitive; for example, highlyalkoxylated (meth)acrylates. Such plasticizers can be selected from thegroup consisting of ethoxylated bisphenol-A-diacrylate, ethoxylatedtrimethylol propane triacrylate, tripropylene glycol diacrylate,alkoxylated acrylates, tetraethylene glycol diacrylate, neopentyl glycolpro-poxylate diacrylate and polyethylene glycol di(meth)-acrylate.

The plasticizer is suitably used at a concentration in the range of fromabout 30 to about 70% by wt. (based on the total weight of the resin andplasticizer), and preferrably is present at an amount in the range offrom about 40 to about 60% by wt. When contact imagability is importantthe plasticizer can be in the preferred range of from about 60% by wt.or less to about 30%. For contact imagability it is also preferred thatthe weight ratio of the plasticizer:resin be in the range of from about0.65 to about 1.25.

Without the amine stabilizers, the present compositions would have tohave a plasticizer that did not swell or dissolve the resin at ambientconditions. In this respect the instant compositions have an advantageover known plastisols which must be limited to plasticizers that do notreadily swell or dissolve the resins. By including the tertiary aminestabilizers the present compositions can use any plasticizingethyllenically unsaturated photopolymerizable acrylate species. The useof the tertiary amine stabilizer allows the use of plasticizers thatwill swell, and even gradually dissolve the resin without the stabilizerpresent.

The tertiary amine stabilizer will act to stabilize and provide anextended shelf life for the plastisol, for any plasticizer-resincombination used. Even the more swellable, more soluble resins will begiven a longer shelf life by the amine stabilizer. The more preferredcombinations, however, use a less soluble, higher molecular weight resinto provide the most stable plastisol with the longest shelf life.Without the tertiary amine stabilizer, the plastisol compositions wouldhave to be used within at least about 36 hours. The shelf life of theplastisol is the length of time that the plastisol can still be used. Ifthe plastisol gels it is considered no longer usable, and the shelf lifehas ended.

As time passes the viscosity of the plastisol increases, and after suchshort periods of time the viscosity gets too high. It is preferred thatthe viscosity of the instant plastisols be less than about 200,000 cps.The plastisol viscosity is used at a level that is effective to allowthe plastisol to be drawn into a film or layer on a suitable substrate.

The resin is a thermoplastic polymer with an acid number of 110 or more,and a midpoint Tg of 110° C. or better. A good range for the acid numberof the polymer is from 110 up to 290. Preferably, the midpoint Tg is145° C. or more. Preferably, the Tg is in the range of from about 115 toabout 175, and the acid number is in the range of from about 150 toabout 200.

The resin is used in particulate form. The resin particles can be anysize which the plastisol technology includes. Thus, the resin caninclude resin particles down to virtually any size found in a plastisol.A preferred largest particle size of the resin is about 300 microns orless, particularly for a screen printable plastisol, and most preferablythe largest particle size of the resin is about 60 microns or less.Preferably the average particle size is greater than about 1 micron.

Preferred, screen printable plastisols can be prepared having 95% by wt.of the particles in sizes ranging from about 60 to about 1 micron indiameter. Most preferably, the average particle size is in the range offrom 35 to about 1 micron. Where contact imagability is important theaverage particle size preferably is at least about 5 microns indiameter; a preferred range then being from about 60 to about 5 micronsand a most preferred range being from about 35 to about 5 microns.

Any technique used for the preparation of non-PVC resin can be used tomake the resin and prepare the particles for the plastisol. Thisincludes steps such as grinding and milling down the particle sizes.

Any polymer or copolymer having an acid moiety can be used. Preferredresins are higher in molecular weight, and will be less soluble in theplasticizer. While a resin can acceptably have a molecular weight ofabout 25,000 or more (weight average molecular weight), a more preferredmolecular weight is about 35,000 or greater, and most preferably, it isgreater than about 75,000. When less solubility is needed, the molecularweight can be increased. Preferred copolymers have acidic monomersselected from the group consisting of acrylic acid, methacrylic acid,maleic acid half ester, maleic anhydride, fumaric acid, fumaric acidhalf ester, and maleic acid. Other preferred polymers include copolymersof N-alkylacrylamide/alkylaminomethacrylate/alkyl(meth)acrylate/(meth)acrylic acid such asoctylacrylamide/acrylate/butylaminoethyl methacrylate polymer(amphomer). The resin can be selected from the group consisting of: acopolymer of styrene and maleic acid half ester and a copolymer ofN-alkylacrylamide/alkylamino (meth)acrylate/(meth)acrylic acid.Preferably the resin is a polymer selected from the group consisting of:polyoctylacrylamide/acrylate/butylaminoethylmethacrylate and styrenemaleic anhydride polymeric ester.

The resin is suitably used at a concentration in the range of from about30 to about 70% by weight (based on the total amount of the resin andplasticizer), and preferably is present at an amount in the range offrom about 40 to about 60% by wt. When contact imagability is importantthe most preferred range is from about 40 to about 70% by wt.

The tertiary amine stabilizers are particularly good for giving shelfstability to plastisols of non-PVC resins (resins that contain nopolymer or copolymer having vinyl chloride monomer). Although, byincluding the tertiary amine stabilizers, plastisols with copolymershaving less than about 80% of the vinyl chloride monomer can also begiven an extended shelf life. Copolymers of vinyl chloride monomer canbe included in amounts which allow aqueous alkali developability. Othermonomers which can be used in the resin copolymers in the instantplastisols are olefin having terminal unsaturation, ethylene, propylene,styrene, vinyl toluene, (meth)acrylate esters, vinyl acetate, and otherterminally unsaturated esters (such as acrylate esters). Such copolymersand monomers are included in amounts which are effective to permitaqueous alkali developability.

The tertiary amine stabilizer is a weak base. The plastisol stabilizeracceptably is selected from the group consisting of triethyl amine,4-methyl morpholine, and an N-butyl diethanol amine and dimethylaminoethanol. Preferred stabilizers are selected from the groupconsisting of triethyl amine, and 4-methyl morpholine. An effectiveamount of the amine stabilizer will maintain coatability for an extendedperiod of time. Acceptably, the amine stabilizer can be used in anamount of from about 1 to about 10 (phr). A preferred amount ofstabilizer in the plastisol is from about 1.5 to about 4 (phr) parts byweight per hundred parts of resin.

With the present invention the stabilizer (preferably 4-methylmorpholine) extends the useful life of plastisols. Problems such asgelling and solubilization of the resin particles are deterred and evenprevented. Such highly preferred tertiary amine stabilizers are goodwhere the plastisol or organosol contains some very small particles(even less than 0.1 micron).

The instant plastisols will also contain a photoinitiator. Thephotoinitiator is acceptably used at an amount in the range of fromabout 1 to about 15% by wt. and preferably it is at an amount in therange of from about 2 to about 12% by wt. Any initiator of thephotopolymerization reaction can be used. Preferred photoinitiators alsoact as a photosensitizer. One or more photoinitiators or aphotoinitiator and a sensitizer can be used. Conventionally used andavailable initiators and systems are also suitable.

Suitable photoinitiators include benzoin and benzoin derivatives such asbenzoin ethers; substituted benzoins and substituted derivatives likebenzilketals and benzoyldiaryphosphine oxides that are known, effectivephotoinitiators. Preferred initiators are those of the benzophenone typeand derivatives thereof such as benzophenone,4,4-dimethylaminobenzophenone, 4,4-diethylaminobenzophenone, orderivatives of Michler's ketone, 4,4-dichlorobenzophenone andhexaarylbisimidazoles. Sensitizing agents that can be combined includecompounds such as 2-mercaptobenzoquinazole, substituted or unsubstitutedpolynuclear quinones such as anthraquinone, benzanthraquinone,2-ethylanthraquinone, and tertbutylanthraquinone and acridine orphenacine derivatives which are also effective photoinitiators.Preferred photoinitiators are to be selected from the group consistingof isopropyl thioxanthone and2-methyl-1[4(methylthio)phenyl]-2-morpholinopropane. Most preferablythese two are combined.

The organosol is a colloidal dispersion of a synthetic resin in aplasticizer in which the dispersion's volatile content exceeds 5% of thetotal (Hawley's Condensed Chemical Dictionary, 11th edition, publishedby Van Nostrand Reinhold Co., New York, 1987).

The diluent included in the organosol is nonreactive. It is non-swellingwith respect to the resin, and is miscible with the plasticizer. Thediluent is volitilizable, (driven off with heat).

Suitably the diluent (also called a "solvent") can be included atamounts up to 10% by wt. of the composition. The maximum amount ofdiluent to be included in the plastisol is about 10% by weight becauselarge amounts of diluent result in phase separation. Thus, the diluentin the organosol is from 5% to about 10% by weight of the coatingcomposition. Aliphatic hydrocarbon solvents can be used. Preferredsolvents are mineral spirits taken from the odorless boiling range.

Other ingredients that can be included in the plastisols and organosolsinclude photosensitizers, pigments, thermal polymerization inhibitors,flow aids, dyes, anti-foams and surfactants.

If a separate photosensitizer is used it can be added in amounts up toabout 5% by wt. Dyes can be used in the amounts effective to color andsurfactants can also be used in amounts needed. Thermal polymerizationinhibitors such as phinothiazine, mono methyl ether of hydroquinone,hydroquinone can be included. Thermal polymerization inhibitors suitablycan be included in amounts effective to prevent thermal reaction. Theycan be used in amounts up to about 1 phr.

These plastisol compositions are excellent solder masks andphotoresists. To prepare a resist or solder mask, the plastisol is drawninto a layer which is then fused with heat. The layer can then bephotoimaged, and then developed with aqueous base. Excellent resolutioncan be obtained.

EXAMPLES

The examples which follow are offered to illustrate the instantinvention and not to limit it. All parts and percentages are by weightunless otherwise indicated.

Plastisol Preparation

The plastisols in the following examples were prepared in accordancewith the following description.

First, the ethylenically unsaturated plasticizer(s) used in each examplewas combined with the photoinitiator(s) and the following additives whenthey were used: free radical thermal polymerization inhibitors, flowagents, bubble breakers, and pigments. When needed in order to dissolvesolids materials such as the free radical thermal polymerizationinhibitors, a small amount of heat was used.

Thereafter, the solution was cooled, and where the tertiary amine wasused, it was added to the solution after it had cooled to approximatelyroom temperature. Stirring was maintained while the tertiary amine wasadded. In all of the cases, the resin was then added slowly withvigorous stirring until it was dispersed, thus forming the plastisol.

Example 1

The ethylenically unsaturated plasticizers used were:

    ______________________________________                                                              Amount                                                  ______________________________________                                        Ethoxylated Bisphenol-A-diacrylate                                                                    34.8 g                                                  (Sartomer 349)                                                                Ethoxylated Trimethylenol Propane Triacrylate   60 g                          (Sartomer 454)                                                              ______________________________________                                    

To the liquid plasticizers, the following solids ingredients were addedand dissolved with slight warming.

    ______________________________________                                        Ingredient               Amount                                               ______________________________________                                        2-Methyl-1[4(methylthio)phenyl]-2-morpholino-                                                          12 g                                                   propane (photoinitiator)                                                      (Irgacure 907-Ciba-Geigy)                                                     Isopropylthioxanthone (photoinitiator) 4 g                                    (Quantacure ITX from Ward Blenkinsop)                                         Phenothiazine .01 g                                                           UV Green Pigment Paste (Pennco color 4 g                                      Pennco green 965)                                                           ______________________________________                                    

Also added was a liquid resin modifier (Moda-flow by Monsanto) in anamount of 2 grams (g).

Styrene maleic anhydride polymeric ester resin (Scripset 550 byMonsanto) was used in the amount of 102 grams.

After the plastisol was prepared, the viscosity (wt. average) wasmeasured using the Brookfield Viscometer at 5 RPM, #6 spindle. Theinitial viscosity was measured at 140,000 cps at 75° F.

This plastisol was screen printed onto a cleaned copper-clad laminateand then was fused for 40 minutes at 140° C.

The film which was prepared was then contact photoimaged. It was coveredwith artwork and exposed with 170 mj of UV radiation. The unexposedareas were then removed with a 1% aqueous sodium carbonate solution. Theremaining film was then post-cured with 3.5 J of UV radiation from ahigh pressure mercury vapor lamp and then was baked for one hour at 150°C.

The solder mask which resulted was a hard tough film with good chemicalresistance of thermal properties.

The unused portion of this formulation gelled in a few days (less than aweek). After gelling it was not coatable and could not be used.

Example 2

The same formulation was used as is described in Example 1. An amount of5 grams of the stabilizer 4-methylmorpholine was added. As a result, theinitial viscosity was lowered to 17,200 cps.

The composition thus prepared was coated and processed as previouslydescribed in Example 1. The solder mask which resulted was a hard toughfilm with good chemical resistance and thermal properties.

The formula prepared under Example 2, however, was still screenprintable after 12 months of aging.

EXAMPLE 3

The following premix was prepared:

    ______________________________________                                                             Amounts                                                    Ingredients (in grams)                                                      ______________________________________                                        Plasticizer (Sartomer 349)                                                                         800.0                                                      Plasticizer (Sartomer 295) 260.0                                              Pentaerythritol tetraacrylate                                                 Plasticizer (Sartomer 9040) 150.0                                             Alkoxylated Diacrylate ester                                                  Phenothiazine free Radical Inhibitor 1.250                                    Irgacure 907 (Photoinitiator) 100.0                                           Quantacure ITX (Photoinitiator) 25.0                                          Green PG5 paste (pigment) 50.0                                                Modaflow (surfactant) 25.0                                                    BB3056A bubble breaker 25.0                                                 ______________________________________                                    

Once the premix was cooled 60.0 g of 4-methylmorpholine was added withstirring, followed by 1250 g of Scripset 550 which was ground in a ballmill until the largest particle was less than 65 microns. The 24 hr.viscosity was 62000 cps (10 rpm, #6 spindle, 25° C.).

The resulting plastisol was screen printed onto a multilayer surfacemount circuit board using a 140T polyester screen and a 70 durometersqueegee. The first side was vertically racked and fused for 15 minutesat 230° F. This was repeated for the second side.

The circuit boards were photoprinted using a Mimir exposure with a lampintensity of approximately 10 mw/cm². They were given 300 mj exposureand a Stouffer step of 11-12 was obtained. Following exposure thenegative is removed from the mask and the unexposed, uncured solder maskwas washed from the circuit board exposing the pads and cleaning out ofthe holes. This development was carried out in 3 minutes using an ASIhorizontal developer containing a 1% aq. sodium carbonate solution at106° F. After developing the boards were water rinsed and hot air dried.They were then given a UV bump of 3.5 J/cm² followed by a post bake of300° F. for 75 minutes. The resist protected circuit board was thensoldered using a commercial hot air leveling equipment and an aqueousflux. Inspection of the board showed the cured solder resist withstoodthe soldering environment and adhered well to the board.

Example 4

A clear solder mask was prepared. The following ingredients were mixedwith slight warming.

    ______________________________________                                                             Amounts                                                    Ingredients (in grams)                                                      ______________________________________                                        Plasticizer Sartomer 349                                                                           80.0                                                       Plasticizer Sartomer 295 26.0                                                 Plasticizer Sartomer 9040 19.0                                                Phenothiazine (free radical inhibitor) 0.1250                                 Irgacure 907 (photoinitiator) 10.0                                            Quantacure ITX (photoinitiator) 2.5                                           Modaflow (surfactant) 2.5                                                     BB3056A bubble breaker 2.5                                                  ______________________________________                                    

After cooling 6 g of 4-methylmorpholine was changed and mixed. Then, 125g of ground Scripset 550 (ground as described in Example 3) was changedwith stirring. The initial viscosity was 39,300 cps at 25° C., 10 rpmNo. 6 spindle.

A mask was screen printed with a 124 mesh polyester screen onto a copperclad laminate. It was fused for 30 minutes at 250° F. to a tackfreefilm. The mask was photoimaged using a Co-light exposure unit for 70seconds under vacuum. It was given an exposure of 189 mj/cm². Theuncured areas were washed away in 3 minutes using a 1% aqueous sodiumcarbonate solution at 105° F. and 30 psi of pressure. The board wasrinsed with water and hot air dried. The mask was UV bumped at 3.5 J/cm²and post baked for 1 hour at 300° F. The resulting mask had a crosshatchadhesion of 4.5 out of 5 and showed it could withstand a methylenechloride for 4 minutes, 13 seconds, before it started to swell the finelines of the IPC test pattern.

Example 5

Plastisols were prepared using triethylamine as the stabilizer.

In accordance with previously given plastisol preparation the samples A,B and C were prepared:

For Sample A: 2000 g Sartomer 349, 1900 g Photomer 4028 (ethoxylatedBisphenol A diacrylate), 440 g Sartomer 454, 400 g tripropylene glycoldiacrylate (Sartomer 306), 5.0 g phenothiazine, 500 g Irgacure 907photoinitiator, 200 g Quantacure ITX photoinitiator and 200 g of GreenPG5 paste pigment. To 155.9 g of this premix 5.0 g (2 phr) oftriethylamine and 127.5 g of ground Scripset 550 (ground as described inExample 3) were charged with stirring. The 24 hr. viscosity was 65,200cps, the 3 day viscosity was 78,400 cps and the 13 day viscosity was127,600 cps.

For Sample B: 6.0 g (2-4 parts per hundred parts of resin phr) oftriethylamine was used with the ingredients of Sample A. The 24 hr.viscosity was 109,400 cps, the 3 day viscosity was 128,000 cps and the13 day viscosity was 188,000 cps.

For Sample C: 7.5 g (3.5 phr) of triethylamine was used with theingredients of Sample A.

The 24 hr. viscosity was 113,600 cps, the 3 day viscosity was 134,800cps and the 13 day viscosity was 254,800 cps.

Example 6

An admixture (pre-mix) was prepared of the following:

    ______________________________________                                        Ingredient          Amount                                                    ______________________________________                                        Startomer 349       1540       g                                                Photomer 4028 1190 g                                                          S-9035 308 g                                                                  Startomer 306 140 g                                                           (Tripropylene Glycol Diacrylate)                                              Phenothiazine 3.5 g                                                           Irgacure 907 350 g                                                            Quantacure ITX 140 g                                                          Modaflow 35 g                                                                 Bubble Breaker 17.5 g                                                         Green PCW 965 Paste 140 g                                                     Exxon Mineral Spirits 140 g                                                 ______________________________________                                    

Using this premix the following organosol formulations were prepared(amounts in grams).

    ______________________________________                                        Sample        A           B      C                                            ______________________________________                                        Premix        80.6        80.6   80.6                                           4-Methyl Morpholine 1.5 2.0 2.5                                               Amphomer 62.5 62.5 62.5                                                     ______________________________________                                    

Amphomer--an acrylic resin (Chemical Name:Octylacrylamide/acrylate/butylamino ethyl methacrylate polymer)

    ______________________________________                                        Viscosity Measurements                                                                A             B        C                                              ______________________________________                                         1 rpm  42,000 cps    36,000 cps                                                                             33,000 cps                                       10 rpm 41,200 cps 34,800 cps 33,600 cps                                     ______________________________________                                    

Viscosity measurements at 25° C., 24 hr., #6 spindle.

The samples were then coated on a copper circuit board and then fusedfor 30 min. at 115° C. to form a dry homogeneous film.

Example 7

Using the previously described method, the following plastisols wereprepared:

SAMPLE A

    ______________________________________                                                            Amount                                                      (grams)                                                                     ______________________________________                                        Plasticizers                                                                    Startomer 349 101                                                             Startomer 252 10                                                              (polyethylene glycol dimethlacrylate)                                         Startomer 9040 10                                                             Other Ingredients                                                             Modaflow 25                                                                   Irgacure 907 12.5                                                             Quantacure ITX 5                                                              Phenothiazine 0.125                                                           Green Paste 5                                                                 Bubble Breaker 2.5                                                            Ground Scripset 550 125                                                       4-methyl Morpholine 6.0                                                     ______________________________________                                    

3 day viscosity--120,000 cps at 1 rpm and 64,000 cps at 10 rpm.

Sample B

Using the identical ingredients indicated for Sample A above, thefollowing plasticizers were used:

    ______________________________________                                                               Amount                                                   Plasticizers (grams)                                                        ______________________________________                                        Startomer 349          100                                                      Startomer 454 11                                                              Startomer 4127 10                                                             (Neopentylglycol propoxylate diacrylate)                                    ______________________________________                                    

24 hr. viscosity--1 rpm--49,000 cps at 10 rpm--46,600 cps.

Sample 7 (Cont'd.) Sample C

A plastisol coating composition was made with 127.5 grams (g.) of thescripset 550 resin, the other ingredients indicated for Sample A, andthe following plastizers:

    ______________________________________                                        Plasticizer       Amount                                                      ______________________________________                                        Startomer 349     43.5                                                          Glycerolproxy triacrylate 75.0                                              24 hr. viscosity at 25° C. (Brookfield - set as                          previously indicated) was:                                                    62,000 cps - 1 rpm                                                            35,500 cps - 10 rpm                                                         ______________________________________                                    

Sample D

The ingredients listed above for Sample A were combined with thefollowing plasticizers.

    ______________________________________                                        Plasticizer           Amount                                                  ______________________________________                                        Photomer 4025         80                                                        (ethoxylated bisphenol A diacrylate)                                          Startomer 295 26                                                              Startomer 9040 15                                                           24 hr. viscosity (#6 spindle) @ 25° C.:                                  72,000 cps @ 1 rpm                                                            48,300 cps @ 10 rpm                                                         ______________________________________                                    

Example 8

The following ingredients were combined with vigorous stirring until theresin particles were dispersed in the liquid ingredients. After a periodof time in excess of two years, this plastisol was still liquid andcoatable. The Scripset S550-F was a finer grind of the S550 Scripset.

    ______________________________________                                                             Amount                                                     Ingredients (in grams)                                                      ______________________________________                                        resin, Scripset S550-F                                                                             1325                                                       diacrylate plasticizer 550                                                    (Startomer SR-349)                                                            Photomer 4028 425                                                             (ethoxylated bisphenol A diacrylate)                                          triacrylate plasticizer 110                                                   (Startomer SR-454)                                                            acrylated plasticizer 50                                                      (Startomer SR-306)                                                            acrylated plasticizer 40                                                      (Startomer SR-351)                                                            photoinitiator 125                                                            (IRG-907)                                                                     photoinitiator 50                                                             (Quantacure ITX)                                                              phenothiazine 1.125                                                           solid 9G5 green pigment 10                                                    4-methylmorpholene 60                                                         carboxybenzotriazole 25                                                       mineral spirits 50                                                            BB3056A bubble breaker 6.25                                                 ______________________________________                                    

What is claimed is:
 1. A photopolymerizable, aqueous developable,plastisol photoresist and solder mask coating composition comprising(1)a plasticizer which is an ethylenically unsaturated photopolymerizablemonomer, (2) a particulate, thermoplastic resin which is soluble ordispersible in a basic aqueous solution and has a midpoint Tg greaterthan 110° C. and an acid number greater than 110, at an amount in therange of from about 30 to about 70% by weight of the total weight of theresin and plasticizer wherein further the plasticizer is present at anamount in the range of from about 70 to about 30% by total weight of theresin and plasticizer, wherein the resin is selected from the groupconsisting of a copolymer of styrene and maleic acid half ester and acopolymer of N-alkylacrylamide/alkylamino(meth)acrylate/(meth)acrylicacid, (3) a tertiary amine stabilizer which is present at an amount inthe range of from about 1 to about 10 parts by weight per hundred partsof resin, and is selected from the group consisting of triethyl amine,N-butyl diethanol amine, 4-methyl morpholine, and dimethyl aminoethanol,and (4) a photoinitiator.
 2. The plastisol of claim 1 wherein thetertiary amine stabilizer includes the 4-methyl morpholine.
 3. Theplastisol of claim 1 wherein the plasticizer is(a) water sensitive, (b)has two or more acrylate species, or (c) is both water sensitive and hastwo or more acrylate species.
 4. The plastisol of claim 1 wherein thephotoinitiator is isopropyl thiozanthone with2-methyl-1-2-morpholinopropane.
 5. The plastisol of claim 1 wherein theresin has a maximum particle size of about 300 microns or less.
 6. Theplastisol of claim 1 wherein the resin does not contain vinyl chloridemonomer and the tertiary amine stabilizer is 4-methyl morpholine,triethyl amine or a mixture of both.
 7. The plastisol of claim 1 whichis contact imagable with a plasticizer:resin ratio in the range of fromabout 0.65 to about 1.25 wherein the plasticizer is present at an amountof from about 60 to about 30% by weight.
 8. A photopolymerizable,aqueous developable, plastisol photoresist and solder mask coatingcomposition comprising(1) a plasticizer which is an ethylenicallyunsaturated photopolymerizable monomer, (2) a particulate, thermoplasticresin, said resin being a copolymer of styrene and maleic acid halfester having a midpoint Tg greater than 110° C. and an acid numbergreater than 110, said resin being present at an amount in the range offrom about 30 to about 70% by weight based on the total weight of theresin and plasticizer wherein the plasticizer is present at an amount inthe range of from about 30 to about 70% by total weight of the resin andplasticizer, (3) a tertiary amine stabilizer which is present at anamount in the range of from about 1 to about 10 parts by weight perhundred parts of resin, and is selected from the group consisting oftriethyl amine, N-butyl diethanol amine, 4-methyl morpholine, anddimethyl aminoethanol, and (4) a photoinitiator.
 9. The plastisolphotoresist and solder mask coating composition of claim 8 wherein thetertiary amine stabilizer is 4-methyl morpholine.
 10. The plastisolphotoresist and solder mask coating composition of claim 8 wherein thetertiary amine stabilizer is triethyl amine.
 11. The plastisolphotoresist and solder mask coating composition of claim 8 which iscontact imagable, having a plasticizer:resin ratio in the range of fromabout 0.65 to about 1.25 wherein the plasticizer is present at an amountof from about 60 to about 30% by weight.
 12. A photopolymerizable,aqueous developable, plastisol photoresist and solder mask coatingcomposition comprising(1) a plasticizer which is an ethylenicallyunsaturated photopolymerizable monomer, (2) a particulate, thermoplasticresin, said resin being an octylacrylamide/acrylate/butylaminoethylmethacrylate polymer having a midpoint Tg greater than 110° C. and anacid number greater than 110, at an amount in the range of from about 30to about 70% by weight based on the total weight of the resin andplasticizer wherein the plasticizer is present at an amount in the rangeof from about 30 to about 70% by total weight of the resin andplasticizer, (3) a tertiary amine stabilizer which is present at anamount in the range of from about 1 to about 10 parts by weight perhundred parts of resin, and is selected from the group consisting oftriethyl amine, N-butyl diethanol amine, 4-methyl morpholine, anddimethyl aminoethanol, and (4) a photoinitiator.
 13. The plastisolphotoresist and solder mask coating composition of claim 12 wherein thetertiary amine stabilizer is 4-methyl morpholine.
 14. The plastisolphotoresist and solder mask coating composition of claim 12 wherein thetertiary amine stabilizer is triethyl amine.
 15. The plastisolphotoresist and solder mask coating composition of claim 12 an which iscontact imagable, having a plasticizer:resin ratio in the range of fromabout 0.65 to about 1.25 wherein the plasticizer is present at an amountof from about 60 to about 30% by weight.